Insert material of air bag cover

ABSTRACT

An insert plate is formed by a base portion, a coupling portion and a mesh material. Notches are formed on both sides of a connecting position at which the coupling portion and the base portion are connected. Accordingly, a line which connects bottoms of the respective notches is defined as a position of a center of unfolding of an unfolding portion of an air bag cover. Since a plurality of slits are formed in the coupling portion to weaken the coupling portion, the unfolding portion can be reliably unfolded about the line for which connects the bottoms of the respective notches. Further, ends of adjacent slits are staggered to prevent a crack from spreading along the entire coupling portion even if the coupling portion is cracked.

This application is a Continuation of Ser. No. 07/945,150, filed Sep.15, 1992, now abandoned.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an insert material embedded in an airbag cover including an unfolding portion which is unfolded by a bag bodyswelling toward a driver when a vehicle is rapidly decelerated.

2. Background Information

In an air bag apparatus, for example, in an air bag apparatus of a typewhich is mounted on a steering wheel, a circular hole 100 is formed inan intermediate portion of a substantially box-shaped base plate 102 asshown in FIG. 7. An unillustrated inflator is arranged in the circularhole 100 of the base plate 102 to emit gas when a vehicle is rapidlydecelerated. A substantially frame-shaped insert plate 104 is fittedwith the base plate 102, and they are connected with each other by anunillustrated bolt or the like. The insert plate 104 is embedded in anair bag cover 106 (see FIG. 6) by insert molding. The insert plate 104is provided with a rectangular frame-shaped base portion 104A, a pair ofmesh materials 104B and 104C embedded in unfolding portions 106A and106B of the air bag cover 106 as will be described below, and couplingportions 104D and 104E coupling the base portion 104A with the meshmaterials 104B and 104C. The mesh materials 104B and 104C serve toprevent the unfolding portions 106A, 106B of the air bag cover 106 fromscattering. The unfolding portions 106A, 106B of the air bag cover 106are unfolded by an unillustrated bag body swelling toward a driver.

However, as shown in FIG. 6, if the above-mentioned air bag cover 106 isunfolded when the vehicle is rapidly decelerated, the coupling portions104D and 104E (which are also shown in FIG. 6) coupling the meshmaterials 104A, 104B with the insert plate 104 are defined as centerpositions about which the air bag cover 106 unfolds. Accordingly, asubstantial opening width at a time when the bag body is swelled becomesnarrow and is equal to a distance P between inner surfaces of theunfolding portions 106A and 106B of the air bag cover 106. Therefore, inconventional air bag apparatus, nain cloth forming the bag body has highstrength so that the bag body swelling out of the opening having thenarrow width is not damaged. As a result, there are some drawbacks suchas the bag body being manufactured at a high cost.

In order to overcome the drawbacks, as shown in FIG. 5, an air bag cover110 may be made large so as to provide an opening width Q larger thanthe opening width P at a time when the respective unfolding portions110A and 110B unfold. However, if the air bag cover 110 itself isenlarged, there is another drawback in that degree of freedom indesigning the air bag cover 110 is reduced.

SUMMARY OF THE INVENTION

In view of the facts set forth above, it is an object of the presentinvention to provide an insert material of an air bag cover so as toprovide a larger opening width when the air bag cover unfolds, withoutemploying a large-sized air bag cover.

An insert material of the present invention is embedded inside an airbag cover having an unfolding portion which is unfolded by a bag bodyswelling toward a driver when a vehicle is rapidly decelerated, andwhich is connected to a base member containing the bag body between thebase member and the air bag cover. The insert material includes a baseportion positioned on the side of the base member, a supporting portionembedded inside the unfolding portion in the same way as the baseportion, and a coupling portion for coupling the base portion and thesupporting portion. The insert material is provided with shift means ofa position of center of unfolding which are provided on both sides of aconnecting position at which the base portion and the coupling portionarc connected, for shifting a position of a center of unfolding of theunfolding portion from an end of the base portion on a side of thedriver toward a side opposite to the driver by a predetermined length,and a plurality of weakening portions provided in the coupling portionat predetermined intervals along a direction intersecting a swellingdirection of the bag body and provided such that adjacent ends of theweakening portions are staggered with respect to the swelling directionof the bag body, so as to reduce rigidity of the coupling portion.

According to the present invention constructed as set forth above, theshift means of a position of a center of unfolding are provided on bothsides of the connecting portion at which the base portion and thecoupling portion of the insert material embedded in the air bag coverare connected. Further, the coupling portion of the insert material isprovided with the plurality of weakening portions at predeterminedintervals in the direction intersecting the swelling direction of thebag body. The unfolded portion of the air bag cover is unfolded by thebag body swelling toward the driver when the vehicle is rapidlydecelerated. At this time, the position of the center of unfolding isshifted by the shift means of a position of a center of unfolding, fromthe end of the base portion of the insert material on the side of thedriver toward a side opposite to the driver by the predetermined length.In addition, the coupling portion is provided with the weakeningportions to reduce the rigidity of the coupling portion. Consequently,the unfolding portion can be reliably unfolded at the shifted positionof the center of unfolding. As a result, it is possible to provide alarger opening width than a conventional opening width when theunfolding portion of the air bag cover unfolds, without employing alarge-sized air bag cover. Hence, the swelling operation of the bag bodyoccurs smoothly. Further, the coupling portion is provided with theplurality of weakening portions, and the respective ends of adjacentweakening portions are staggered along the swelling direction of the bagbody. Accordingly, even if the coupling portion weakened by theweakening portions is cracked due to the unfolding force of theunfolding portion, cracks do not form between the respective ends ofadjacent weakening portions. Therefore, the unfolding portion is neverbroken due to the cracks forming along the entire the coupling portionof the insert material.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an insert plate showing one embodimentof an insert material of an air bag cover of the present invention;

FIG. 2 is a sectional view showing an unfolded condition of the air bagcover equipped with the insert plate of FIG. 1;

FIG. 3 is a schematic sectional view of an air bag apparatus equippedwith the insert plate of FIG. 1 and mounted on a steering wheel;

FIG. 4 is a perspective view corresponding to FIG. 1, showing a modifiedembodiment of the insert plate of FIG. 1;

FIG. 5 is a sectional view corresponding to FIG. 2, showing an unfoldedcondition of unfolding portions in a conventional air bag apparatushaving a large-sized air bag cover;

FIG. 6 is a sectional view corresponding to FIG. 2, showing an unfoldedcondition of unfolding portions in a conventional air bag apparatushaving a standard size air bag cover; and

FIG. 7 is a perspective view corresponding to FIG. 1, showing the insertplate embedded in the conventional air bag cover of FIG. 6.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

An air bag apparatus 10 in a preferred embodiment will be describedhereinafter with reference to FIGS. 1 to 3.

The air bag apparatus 10 is mounted on a hub 12A of a steering wheel 12as shown in FIG. 3. The air bag apparatus 10 is provided with asubstantially box-shaped base plate 14, and a circular hole 16 (seeFIG. 1) is formed in a central portion of the base plate 14. An inflator18, a bag body 20 and an insert plate 24, which is embedded in an airbag cover 22 and serves as an insert material, are mounted on the baseplate 14.

The inflator 18 is provided in a substantially cylindrical form. Aflange 26 is formed on an axially intermediate portion of the inflator18. The flange 26 has a square form as seen from above. The inflator 18is arranged so as to pass through the circular hole 16 from the side ofthe base plate 14 opposite to a driver. The inflator 18 includes anunillustrated starting apparatus, an unillustrated detonator, anunillustrated booster, an unillustrated gas generating material and thelike. The starting apparatus a state of rapid deceleration of thevehicle. The detonator is ignited by the actuating of the startingapparatus. The booster serves to promote the growth of a spark of thedetonator. The gas generating material generates a large quantity of gaswhen burned through the booster. The gas is emitted from a plurality ofgas holes 28 into the bag body 20 as will be described hereinafter. Thegas holes 28 are provided on a peripheral surface of the inflator 18 onthe side of the driver.

The bag body 20 is in a folded condition and is contained between theair bag cover 22 and the base plate 14. A circular opening portion isformed in a portion of the bag body 20 on the side opposite to thedriver, and a ring plate 30 is arranged inside the opening portion. Thering plate 30 is clamped with the base plate 14 and the flange 26 of theinflator 18 by an unillustrated bolt or the like. Accordingly, aperipheral edge of the opening portion of the bag body 20 is pressedagainst the base plate 14.

The air bag cover 22 has a substantially box-shaped form, and has anH-shaped thin-walled portion 32 (see FIG. 3) which is provided on asurface of the air bag cover 22 on the side of the driver. When thevehicle is rapidly decelerated, the air bag cover 22 is broken at thethin-walled portion 32. Thus, the thin-walled portion 32 is broken, andthe air bag cover 22 is separated into a pair of unfolding portions 22Aand 22B (see FIG. 2). The pair of unfolding portions 22A, 22B unfold indirections of moving away from each other. An insert plate 24 isembedded in the air bag cover 22 by insert molding.

Referring now to FIG. 1, the insert plate 24 is provided with a baseportion 24A having a substantially rectangular frame-shaped form. Aheight H of the base portion 24A is identical to a height H' of the baseportion 104A of the conventional insert plate 104 (see FIG. 7). Aplurality of mounting holes 34 are formed in a pair of opposite sideportions of the base portion 24A to mount the base portion 24A on thebase plate 14. Mesh materials 24C serving as supporting portions areintegrally formed with the side portions through coupling portions 24B.The mesh materials 24C are embedded in the pair of unfolding portions22A and 22B of the air bag cover 22 as shown in FIG. 2. The meshmaterials 24C are provided to prevent resin (for example, urethane) ofthe unfolding portions 22A, 22B from scattering when the unfoldingportions 22A and 22B unfold in directions of moving away from each otherwhen the vehicle is rapidly decelerated.

Notches 36 are formed on both sides of connecting positions at which thecoupling portions 24B and the base portion 24A are connected. Therespective rectangular notches 36 are provided to serve as shift meansof the positions of the centers of unfolding. The notch 36 is notchedsuch that the notched direction thereof is opposed to the swellingdirection of the bag body (i.e., the direction shown by arrow A i nFIGS. 2 and 3 ). Notched length h is equal to about one-third of theheight H of the base portion 24A. The notched length h can beappropriately varied depending upon the strength of the insert plate 24.Lines X--X connecting the bases of the notches 36 are defined aspositions of the centers of unfolding of the unfolding portions 22A,22B.

A plurality of slits 38 and 40, which serve as weakening portions whichweaken the coupling portions 24B, are provided in the coupling portions24B. The longitudinal directions of the slits 38, 40 run along theswelling direction of the bag body 20. These slits 38, 40 are disposedparallel to each other along the direction perpendicular to the swellingdirection of the bag body 20 (i.e., in the direction shown by arrow B inFIG. 1) and are spaced apart at predetermined intervals. Both ends 38A,38B in the longitudinal direction of the slit 38 are respectivelyadjacent to both ends 40A, 40B in the longitudinal direction of the slit40. Further, the ends 38A and 40A and the ends 38B and 40B respectivelyare staggered with respect to each other by a predetermined length alongthe swelling direction of the bag body 20 (i.e., in the direction shownby arrow A in FIGS. 2 and 3). That is, a line for connecting therespective ends 38A and 40A in the longitudinal direction (or the ends38B and 40B in the longitudinal direction) of the slits 38 and 40 can bedescribed as a corrugated curve.

A description will be given of the operation of the embodimenthereinafter.

The starting apparatus is not actuated during the normal travelingcondition of the vehicle so that the air bag apparatus 10 is notactuated. Accordingly, the unfolding portions 22A and 22B do not unfold,and the insert plate 24 is also left in the condition shown in FIG. 1.

If the vehicle in this condition is rapidly decelerated, the startingapparatus is actuated to emit a large amount of gas from the inflator 18into the bag body 20. Consequently, the bag body 20 is swelled to pressthe unfolding portions 22A and 22B in the swelling direction of the bagbody 20 (i.e., in the direction shown by arrow A in FIG. 2) fromsurfaces of the unfolding portions 22A and 22B on the side opposite tothe driver. The thin-walled portion 32 of the air bag cover 22 isthereby broken so that the pair of unfolding portions 22A, 22B unfold indirections of moving away from each other.

At this time, the lines X--X for connecting the bases of the notches 36of the base portion 24A (see FIG. 1) serve as the positions of thecenters of unfolding of the unfolding portions 22A and 22B, because thepair of notches 36 are formed at the connecting positions at which thecoupling portion 24B and the base portion 24A are connected. Inaddition, since the plurality of slits 38, 40 are formed in the couplingportions 24B, the rigidity of the coupling portions 24B decreases, andthe coupling portions 24B are weakened. Therefore, no resistance isprovided to the unfolding operation of the unfolding portions 22A, 22B,and the lines X--X can be reliably defined as the positions of thecenters of unfolding of the unfolding portions 22A and 22B. Accordingly,it is possible to smoothly unfold the unfolding portions 22A, 22B indirections of moving away from each other with the lines X--X as centersof the unfolding. The X--X lines serve as the positions of the centersof unfolding, and extend across positions of the base portion 24A whichare notched by the length h from an end surface of the base portion 24Aon the side of the driver in the direction opposite to the driver. As aresult, though the air bag cover 22 itself is the same size asconventional air bag covers, it is possible to provide a larger openingwidth R for the swelling of the bag body 20 than the conventionalopening width P. Consequently, the bag body 20 can swell smoothly, andthe swelled bag body 20 is interposed between the driver and thesteering wheel 12.

As described above, in the present embodiment, the pair of notches 36are formed at both sides of the connecting positions at which the baseportion 24A of the insert plate 24 and the coupling portion 24B arcconnected. Accordingly, the positions of the centers of unfolding of theunfolding portions 22A and 22B can be shifted toward the side oppositeto the driver by the notched length h. Further, since the plurality ofslits 38, 40 are formed in the coupling portions 24B, it is possible toreduce the rigidity of the coupling portion 24B, and to reliably shiftthe positions of the centers of unfolding of the unfolding portions 22A,22B to the lines X--X. Therefore, the larger opening width R of the bagbody 20 is provided so that the bag body 20 can swell smoothly.

In the present embodiment, the line for which connects the ends of theslits 38, 40 along the direction perpendicular to the swelling directionof the bag body 20 can be described as a corrugated line. Thus, even ifthe coupling portions 24B are cracked due to the swelling force of thebag body 20, it is possible to prevent the coupling portions 24B frombeing broken due to cracks which extend between the ends of the adjacentslits 38, 40. As a result, breaking of the unfolding portions 22A, 22Bcan be prevented.

In the present embodiment, the mesh materials 24C, the coupling portions24B and the base portion 24A are integrally formed with each other toform the insert plate 24, and the plurality of slits 38, 40 are formedin the coupling portions 24B. However, the present invention should notbe limited to the embodiment, and may be applied to all constructionswhich can weaken the coupling portions 24B and can reliably shift thepositions of the centers of unfolding of the unfolding portions 22A, 22Bto the lines X--X. For example, as shown in FIG. 4, an insert plate 50and a mesh material 52 may be formed separately. Further, the insertplate 50 may be provided with tongue piece-shaped coupling portions 50A,50B and 50C having different longitudinal lengths. These couplingportions 50A, 50B and 50C may be fixed with the mesh material 52 by avis 54. In this case, grooves 56 and upper end opening portions 58 ofthe coupling portions 50A, 50C serve as weakening portions. The grooves56 are respectively disposed between the adjacent coupling portions 50Aand 50B, and between the adjacent coupling portions 50B and 50C. Theupper end opening portions 58 of the coupling portions 50A, 50Ccommunicate with the grooves 56. Moreover, a plurality of small holesmay be formed at the same positions as the positions of the slits 38, 40instead of the slits 38, 40. Alternatively, concave portions or the likemay be provided instead of the slits 38, 40 to provide thin-walledcoupling portions.

In the embodiment, the pair of notches 36 is formed at the connectingpositions at which the coupling portion 24B and the base portion 24A areconnected. However, the present invention should not be limited to theembodiment, and may be applied to all constructions which can shift thepositions of the centers of unfolding of the unfolding portions 22A and22B in the direction opposite to the driver.

What is claimed is:
 1. An insert material embedded inside an air bagcover having an unfolding portion which is unfolded by a bag bodyswelling toward a driver when a vehicle is rapidly decelerated, andconnected to a base member containing said bag body between said basemember and said air bag cover, and including a base portion positionedin a direction of said base member with respect to said air bag cover, asupporting portion embedded inside said unfolding portion in the sameway as said base portion, and a coupling portion for coupling said baseportion and said supporting portion, said insert materialcomprising:shift means of a position of a center of unfolding providedon both sides of a connecting position at which said base portion andsaid coupling portion are connected, for shifting a position of a centerof unfolding of said unfolding portion from an end of said base portionon a side of the driver toward a side opposite to the driver by apredetermined length; and a plurality of weakening portions provided insaid coupling portion at predetermined intervals along a directionintersecting a swelling direction of said bag body and provided suchthat adjacent ends of said weakening portions are staggered with respectto the swelling direction of said bag body, so as to reduce rigidity ofsaid coupling portion and to prevent the detachment of said unfoldingportion from said base member due to the formation of cracks betweenrespective ends of the weakening portions.
 2. An insert materialaccording to claim 1, wherein said shift means of a position of a centerof unfolding is notches which are notched from said end of said baseportion on the side of the driver toward the side opposite to thedriver.
 3. An insert material according to claim 2, wherein said notchesare provided such that a length of each of said notches, from said endof said base portion on the side of the driver, is equal toapproximately one third of a height of said base portion.
 4. An insertmaterial according to claim 3, wherein said base portion, saidsupporting portion and said coupling portion are integrally formed witheach other.
 5. An insert material according to claim 4, wherein saidplurality of weakening portions is provided such that longitudinaldirections thereof run along the swelling direction of said bag body. 6.An insert material according to claim 3, wherein said base portion, saidsupporting portion and said coupling portion are formed separately. 7.An insert material according to claim 6, wherein said plurality ofweakening portions is provided such that longitudinal directions thereofrun along the swelling direction of said bag body.
 8. An insert materialaccording to claim 4, wherein each of said plurality of weakeningportions is formed of a plurality of rows of adjacent circularthrough-holes disposed along the swelling direction of said bag body. 9.An insert material according to claim 5, wherein said plurality ofweakening portions is slits.
 10. An insert material according to claim5, wherein said plurality of weakening portions is thin-walled portionsformed by said coupling portion being notched in a direction ofthickness of said coupling portion.
 11. An insert material according toclaim 7, wherein said plurality of weakening portions is grooves notchedfrom said end of said base portion on the side of the driver toward theside opposite to the driver.
 12. An air bag cover having an unfoldingportion which is unfolded by a bag body swelling toward a driver when avehicle is rapidly decelerated, said air bag cover comprising:an insertmaterial embedded inside said air bag cover, and connected to a basemember containing said bag body between said base member and said airbag cover, and including a base portion positioned in the direction ofsaid base member with respect to said air bag cover, a supportingportion embedded inside said unfolding portion in a same way as saidbase portion, and a coupling portion for coupling said base portion andsaid supporting portion; shift means for a position of a center ofunfolding provided on both sides of a connecting position at which saidbase portion and said coupling portion are connected, for shifting aposition of a center of unfolding said unfolding portion from an end ofsaid base portion on a side of the driver toward a side opposite to thedriver by a predetermined length; and a plurality of weakening portionsprovided in said coupling portion at a predetermined intervals along adirection intersecting a swelling direction of said bag body andprovided such that adjacent ends of said weakening portions arestaggered with respect to the swelling direction of said bag body, so asto reduce rigidity of said coupling portion and to prevent thedetachment of said unfolding portion from said base member due to theformation of cracks between respective ends of the weakening portions.13. An air bag cover according to claim 12, wherein said shift means ofa position of a center of unfolding is notches which are notched fromsaid end of said base portion on the side of the driver toward the sideopposite to the driver.
 14. An air bag cover according to claim 13,wherein said notches are provided such that a length of each of saidnotches, from said end of said base portion on the side of the driver,is equal to approximately one-third of a height of said base portion.15. An air bag cover according to claim 14, wherein said base portion,said supporting portion and said coupling portion are integrally formedwith each other.
 16. An air bag cover according to claim 14, whereinsaid base portion, said supporting portion and said coupling portion areformed separately.
 17. An air bag cover according to claim 15, whereineach of said plurality of weakening portions comprises a plurality ofrows of adjacent circular through-holes disposed along the swellingdirection of said bag body.
 18. An air bag cover according to claim 15,wherein said plurality of weakening portions is slits.
 19. An air bagcover according to claim 15, wherein said plurality of weakeningportions is thin-walled portions formed by said coupling portion beingnotched in a direction of thickness of said coupling portion.
 20. An airbag cover according to claim 16, wherein said plurality of weakeningportions is grooves notched from said end of said base portion on theside of the driver toward the side opposite to the driver.